Cyclic Fatigue Resistance and Surface Roughness of Rotary NiTi Instruments after Simulated Clinical Use in Curved Root Canals - An Atomic Force Microscopy Study

Abstract Objective: To examine the cyclic fatigue resistance and surface topography of TruNatomy and ProTaper Gold nickel-titanium rotary files and evaluate the presence of alterations to surface topography following instrumentation in simulated curved canals. Material and Methods: Twenty-four nickel-titanium instruments, twelve each of TN and PTG file systems, were evaluated for cyclic fatigue resistance. The rotary files were rotated in a simulated root canal with standardized diameter, angle of curvature, and radius of curvature in a custom-made cyclic fatigue testing device until the instrument fracture occurred. The time to fracture for each instrument was recorded with a stopwatch; in seconds in each group. Fractured instruments were subjected to atomic force microscopy analysis measuring the average roughness and the root mean square values to investigate surface features of endodontic files. Mean values and standard deviation were calculated. Data were analyzed using the Mann-Whitney U test. Results: Time to fracture was marginally higher in PTG instruments than in the TN file systems. PTG files exhibited higher surface roughness when compared with TN files (p<0.05). Conclusion: TN file system had a higher cyclic fatigue resistance than PTG. Cyclic fatigue causing file breakage did affect the surface topography of the files. PTG files showed a higher surface porosity value than the TN files (AU).

Awareness and Practices of Minimal Invasive Dentistry amongst Dental Interns - A Descriptive Analysis.

The current approach to management of caries has evolved towards minimal invasive dentistry comprising of early diagnosis of incipient lesions, remineralization and conservative dental treatment with minimal intervention if required. Despite the focus of the dental curriculum on minimal invasive dentistry, not much of it is adopted into practice by the students. We wanted to assess the knowledge, attitude, and skills of minimal invasive dentistry amongst the dental interns of Dakshina Kannada district. MethodsThe data was gathered through an online questionnaire developed and validated by experts. ResultsA total of 244 dental interns responded to the online questionnaire survey. Majority was aware of the principles of minimal invasive dentistry mainly through lectures, although not many had practiced it. Fluoride treatment was the most recommended treatment for the prevention of caries. Although most of them agreed that caries risk assessment was effective, nearly half of them had never practiced it. A greater part of the respondents agreed upon the effectiveness of preventive measures and conservative modalities of treatment in the current day practice. ConclusionsDespite the awareness and knowledge of minimal invasive dentistry amongst the interns of Dakshina Kannada population, the practice of minimal invasive dentistry should be taught to the students and should be implemented in routine dental practice.